"[They] always seem to be on the verge of a breakup over one crisis or another. But now a divorce is imminent," the insider added. "This could be one of Hollywood's most expensive, ugliest and dirtiest divorces ever."

"It was two-fold," the source explained. "Ellen's obsession with controlling Portia's personal life and career, and then Ellen's insistence on not starting a family. That's the biggest hurdle they can't seem to overcome — Portia wanted children and Ellen didn't."

The Oscar host married the Australian-American actress in 2008 at their home in Beverly Hills after the state of California lifted its ban on same-sex marriages. DeGeneres had previously slammed reports that she and Rossi are heading for divorce.

"We don't know anything about it until somebody tells us," she said, according to Entertainment Tonight‎. "I don't read the tabloids, and I don't have a publicist."